In a large bowl, combine the flour, sugar, yeast, and salt. Add the warm water and oil. Mix until a shaggy dough forms. Turn it out onto a floured surface and knead for 8 to 10 minutes until smooth and elastic. Place in an oiled bowl, cover, and let it rest for 1 hour until doubled in size.

While the dough rests, heat a large skillet over medium-high heat. Add a drizzle of oil and cook the garlic and ginger until fragrant, about 30 seconds. Add the ground pork and cook, breaking it up, until browned. Toss in the shredded cabbage. Cook until the cabbage wilts down significantly. Add the chopped noodles, soy sauce, sesame oil, oyster sauce, and white pepper. Stir to combine. Taste and adjust seasoning. Let the filling cool completely.

Punch down the risen dough and divide it into 16 equal pieces. Roll each piece into a ball. On a lightly floured surface, flatten each ball into a 4-inch circle. Place a generous tablespoon of the cooled filling in the center. Pleat the edges of the dough to seal the bun tightly. Place each assembled bun on a parchment-lined baking sheet, seam side down.

Heat a large nonstick skillet over medium heat. Add a generous swirl of oil. Place the buns seam side down into the hot pan, leaving a little space between each one. Listen for the satisfying sizzle. Cook for 2 to 3 minutes until the bottoms are deeply golden brown.

Carefully pour about 1/4 cup of water into the hot skillet. It will splutter, so stand back. Immediately cover the skillet with a tight-fitting lid. Reduce the heat to low and let the buns steam for 8 to 10 minutes. The water will evaporate and the tops will become tender and translucent.

Remove the lid. If there is any remaining water, let it cook off. Let the buns fry for another minute to re-crisp the bottoms. Sprinkle with sesame seeds and sliced green onions. Serve hot.